A person from any large city who does not know how to drive well on roads that aren't straight and flat. You can tell one because when you get stuck behind them on a mountain road they take the curves at a snails pace, but when you finally come to a flat/straight stretch (where you could potentially pass their slow ass) they speed up like crazy till the next curve. Lather, rinse, repeat. --Insult is added to injury when the flat landers have a large truck/SUV/other form of 4-wheel drive and do this.

Used by native Vermonters to describe people from anywhere else in the country, regardless of whether or not your state has a higher elevation than Vermont. If you aren't native to Vermont, you're a flatlander, period. The term came about because of people from other states visiting the state on account of the ski resorts and the mountains.

"Those damn rich flatlanders come up here from freakin' California and buy up all our farmland and develop damn Walmarts all over the place."